MFC r319751: MFV r319740: 8168 NULL pointer dereference in zfs_create()

illumos/illumos-gate@690031d326342fa4ea28b5e80f1ad6a16281519d
https://github.com/illumos/illumos-gate/commit/690031d326342fa4ea28b5e80f1ad6a16281519d

https://www.illumos.org/issues/8168
  If we manage to export the pool on which we are creating a dataset (filesystem
  or zvol) between entering libzfs`zfs_create() and libzfs`zpool_open() call (for
  which we never check the return value) we end up dereferencing a NULL pointer
  in libzfs`zpool_close().
  This was discovered on ZFS on Linux. The same issue can be reproduced on
  Illumos running in parallel:
    while :; do zpool import -d /tmp testpool ; zpool export testpool ; done
    while :; do zfs create testpool/fs; zfs destroy testpool/fs ; done
  Eventually this will result in several core dumps like this one:
  [root@52-54-00-d3-7a-01 /cores]# mdb core.zfs.4244
  Loading modules: [ libumem.so.1 libc.so.1 libtopo.so.1 libavl.so.1
  libnvpair.so.1 ld.so.1 ]
  > ::stack
  libzfs.so.1`zpool_close+0x17(0, 0, 0, 8047450)
  libzfs.so.1`zfs_create+0x1bb(8090548, 8047e6f, 1, 808cba8)
  zfs_do_create+0x545(2, 8047d74, 80778a0, 801, 0, 3)
  main+0x22c(8047d2c, fef5c6e8, 8047d64, 8055a17, 3, 8047d70)
  _start+0x83(3, 8047e64, 8047e68, 8047e6f, 0, 8047e7b)
  >
  Fix and reproducer (systemtap): https://github.com/zfsonlinux/zfs/pull/6096

Reviewed by: Matt Ahrens <mahrens@delphix.com>
Approved by: Robert Mustacchi <rm@joyent.com>
Author: loli10K <ezomori.nozomu@gmail.com>

1 files changed, 3 insertions, 1 deletions

diff --git a/cddl/contrib/opensolaris/lib/libzfs/common/libzfs_dataset.c b/cddl/contrib/opensolaris/lib/libzfs/common/libzfs_dataset.c
index 7ce5cbe..38500b1 100644
--- a/cddl/contrib/opensolaris/lib/libzfs/common/libzfs_dataset.c
+++ b/cddl/contrib/opensolaris/lib/libzfs/common/libzfs_dataset.c
@@ -3316,6 +3316,7 @@ zfs_create(libzfs_handle_t *hdl, const char *path, zfs_type_t type,
 	char errbuf[1024];
 	uint64_t zoned;
 	enum lzc_dataset_type ost;
+	zpool_handle_t *zpool_handle;
 
 	(void) snprintf(errbuf, sizeof (errbuf), dgettext(TEXT_DOMAIN,
 	    "cannot create '%s'"), path);
@@ -3355,7 +3356,8 @@ zfs_create(libzfs_handle_t *hdl, const char *path, zfs_type_t type,
 	if (p != NULL)
 		*p = '\0';
 
-	zpool_handle_t *zpool_handle = zpool_open(hdl, pool_path);
+	if ((zpool_handle = zpool_open(hdl, pool_path)) == NULL)
+		return (-1);
 
 	if (props && (props = zfs_valid_proplist(hdl, type, props,
 	    zoned, NULL, zpool_handle, errbuf)) == 0) {